1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, which carries out a wet process with respect to a semiconductor device whose wiring containing copper or aluminum are exposed.
2. Description of the Related Art
The conventional via hole forming process in the manufacturing process of semiconductor devices will be described below with reference to FIG. 13A to FIG. 13C.
A sample shown in FIG. 13A was prepared. The sample was obtained in the following manner. That is, a Cu wiring 12 was formed in a trench formed in a first interlayer insulating film 10 on a semiconductor substrate (not shown) via barrier metal 11, and a second interlayer insulating film 14 was further formed thereon via a SiC layer 13.
The above second interlayer insulating film 14 and SiC layer 13 were etched by dry etching so that a via hole 15 could be formed. The barrier metal 11 and the Cu wiring 12 were exposed on the bottom surface of the via-hole 15. When the via hole 15 was formed, a Cu reactive layer 16 was formed.
As depicted in FIG. 13B, the Cu reactive layer 16 was removed using a contact hole cleaning liquid 21 such as diluted hydrofluoric acid (DHF). Then, as seen from FIG. 13C, the barrier metal 11 and the Cu wiring 12 were rinsed using pure water 22, and thereafter, dried.
The problems in the conventional technique will be described below with reference to FIG. 14A and FIG. 14B. When the Cu wiring 12 and the barrier metal 11 exposed in forming the via hole come into contact with the solution, a cell circuit is formed. If the potential (ECu) of the Cu wiring 12 is higher than the potential (EBM) of the barrier metal 11, corrosion occurs on the interface between the Cu wiring 12 and the barrier metal 11 (see FIG. 14A). If the potential (ECu) of the Cu wiring 12 is lower than the potential (EBM) of the barrier metal 11, corrosion occurs on the surface of the Cu wiring 12 and the barrier metal 11 (see FIG. 14B). In addition, depending on the kind of contact solution used, corrosion is further accelerated with respect to Cu in the contact solution by synergistic effect with chemical components having etching properties.
In addition, the same problem also as aluminum wiring occurs.
As described above, there is a problem that corrosion occurs in wirings when carrying out a wet process with respect to a semiconductor device on which Cu or Al wirings and other metal material are exposed.